Pump



Sept. 23, 1969 H. snmenan PUMP Filed Jan. 23. 1967 FIG.I

'nwsu'ron v n. scmusaag Wold/# ATTORNEY United States Patent O,"

3,468,261 PUMP Heinz Schmierer, Maichingen, Wurttemberg, Germany,assignor to Altec Gesellschaft fur Allgemeine Landtechnik m.b.H.,Hailfingen, Wurttemberg, Germany Filed Jan. 23, 1967, Ser. No. 611,119Int. Cl. F04]! 43/02; F01b 19/00 US. Cl. 103150 9 Claims ABSTRACT OF THEDISCLOSURE Background of the invention The present invention relates toa pump. More specifically, the invention relates to a diaphragm pump.

It is known to construct diaphragm pumps with a cylinder which defines achamber. The chamber has an end portion and is being bounded by aninternal surface. A flexible diaphragm extends across such end portionand is secured to the cylinder and the piston is reciprocably receivedin the chamber and has an external peripheral surface and end portionwhich is adjacent to and fixed with the diaphragm. Since the diaphragmis constantly flexed during each working and rest stroke of the piston,it is under particular stress at those areas of the diaphragm which aresecured to the cylinder. The diaphragm which consists of an elastomericmaterial, usually a rubber-like substance, makes it necessary indetermining the operating parameters of diaphragm-type pumps to soconstruct the pump that the distance traversed by the piston during theworking and rest strokes thereof can only be relatively small. This, inturn, means that the fluid displacing capacity of such pumps per strokeis very small as compared to pumps of other types. In order to reduce tosome extent at least the stresses which act upon the diaphragm at theareas at which the same is secured to the cylinder, it is known to roundthe internal surfaces of the cylinder end portion or of the piston endportion so that the respective rounded surface defines with the adjacentsurface of the other end portion an annular space adjacent to thediaphragm. This space is either completely or partially filled with ausually liquid lubricant and during the operating stroke of the pistonthe diaphragm is partly elastically displaced into this annular space,thereby displacing the lubricant therefrom. This results in a loss ofthe volumetric capacity of the pump and this decrease in the capacitybecomes larger, the greater the rounding of the surfaces leading toformation of the annular space is selected.

Summary of the invention The present invention overcomes theabove-discussed disadvantages of the prior art.

More specifically, the present invention provides a pump whichsignificantly increases the volumetric capacity despite the limitedstress-resistance of the diaphragm.

In accordance with one feature of my invention I provide a pump, whichincludes a cylinder defining a chamice her having an end portion andbeingbounded by an internal surface. A flexible diaphragm is providedand extends across the end portion of the chamber, and this diaphragm issecured to the cylinder. A piston is reciprocably accommodated in thechamber and is provided with an external peripheral surface and with anend portion adjacent to and fixed with the diaphragm. At least one ofthe aforementioned end portions defines with the adjacent surface of theother end portion an annular space which is located adjacent to thediaphragm. Finally, my novel pump also includes an annular insert ofelastically yieldable material which is received in the aforementionedannular space.

In accordance with the invention, this annular insert may be of circularor non-circular cross-section, with a triangular cross section beingpreferred since this configuration is particularly adapted for fillingthe annular space. Although various different elastic materials aresuitable for the annular insert, cross-linked polyurethene elastomer hasbeen found to be particularly advantageous.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

Brief description of the drawing FIG. 1 is a partial section through adiaphragm-type pump in accordance with the present invention;

FIG. 2 is a fragmentary section, shown in an enlarged view, illustratingthe pump of FIG. 1 during the suction stroke of the piston; and

FIG. 3 is a view substantially similar to FIG. 2, but illustrating thepump of FIG. 1 during the pressure-stroke of the piston.

Description of the preferred embodiments Discussing now the drawing indetail, and firstly FIG. 1 thereof, it will be seen that there is showna diaphragmtype pump which comprises a cylinder 1 in which there isreceived a piston 2 for reciprocable movement therein. The piston 2 canbe given reciprocatory movement in various ways, for instance via apiston rod 11, and a crank or similar member 12 connected with thepiston rod. This is shown in FIG. 1 but only by way of example since itis not essential for the invention. The drive arrangement for the pistonis provided in a drive housing 10 which communicates with the chamberdefined by cylinder 1.

A cover or lid 4 is rigidly connected with the end portion of thecylinder 1 and this cover defines a chamber 5 and carries an inlet valve7 and an outlet valve 6. Arranged between the chamber 5 defined withinthe cover 4 and the chamber which is defined in the cylinder 1, is adiaphragm 3 consisting of elastically yieldable material. Thus, thefluid which is pumped by the pump shown in FIG. 1 and which passesthrough the chamber 5 in the cover 4 cannot come in contact with thepiston 2 or enter into the working chamber defined in cylinder 1 and inwhich the piston 2 reciprocates.

The end portions of the cover 4 as well as of the cylinder 1 arerounded, that is the respective inner circumferential surfaces of theperipheral walls of cover 4 and of cylinder 1 diverge radiallyoutwardly. Similar rounding will be seen to be provided at the endportion of the piston 2 and the rounding of the end portion of thepiston, together with the rounding of the internal surface of theperipheral wall of cylinder 1 and the end portion of the latter resultsin the provision of a hollow annular space 9. In accordance with theinvention, an annular element 8 is disposed in this hollow annular space9, and completely or at least partially fills the cross-section of thesame. This element 8 consists, as pointed out earlier in thisspecification of a suitable elastomeric material, for intsance of across-linked polyurethene elastomer.

FIG. 2 shows that the cross-section of the annular memher 8 may becircular, whereas FIG. 3 shows that the cross-section may be triangular.Of course, neither of these cross-sectional configurations is exclusiveof other possibilities, but circular or triangular cross section ispreferred.

It is evident from FIGS. 2 and 3 that the accommodation of the annularmember, which in FIG. 2 is indicated with reference numeral 8, and inFIG. 3 with reference numeral 8', prevents deflection of the diaphragm3, into the annular space 9, during the working as well as during thereturn stroke, thus eliminating excessive stress on such portions of thediaphragm as are normally deflected precisely into this space.Evidently, the provision of this arrangement not only significantlyincreases the life of the diaphragm over similar constructions knownfrom the prior art but also makes it possible to raise the volumetriccapacity of a pump so constructed, thus representing a significantadvance in the state of the art. As is evident from all of the figures,the diaphragm 3 is secured by being clamped between the juxtaposed endfaces of the cylinder 1 and the cover 4 and can be secured to the piston2 by means of a screw or bolt 13 and a suitable washer 14, if this isdesired. The provision of the inlet valve 7 and the outlet valve 6 hasalready been mentioned, and it will be specifically seen rom FIG. 1 ofthe drawing, that a seat 16 and an abutment 16' are provided for theinlet valve 7 on the cover 4, whereas a similar seat and abutment 15'are provided for the outlet valve 6, also on the cover i 4. This isshown for the sake of completeness only and does not constitute a partof the invention which latter is concerned only with the provision ofthe particular elastomeric annular member 8, 8 in the particular mannerdescribed herein.

It will be understood that each of the elements described above, or twoor more together may also find a useful application in other types ofarrangements, difiering from the types described above.

While the invention has been illustrated and described as embodied in adiaphragm pump, it is not intended to be limited to the details shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

1. A pump, including a cylinder defining an elongated chamber having anend portion and being bounded by an internal surface having apredetermined diameter and flaring continuously outwardly at said endportion of said chamber; a flexible diaphragm extending across said endportion and being secured to said cylinder; a piston reciprocablyreceived in said chamber and having a diameter substantially identicalto said predetermined diameter, said piston further having an externalperipheral surface and an end portion adjacent to said diaphragm, atleast said end portion of said chamber defining with the adjacentsurface of the end portion of said piston adjacent to said diaphragm anannular space the volume of which changes during movement of saidpiston; and an annular insert of elastically yieldable material, havinga diameter at most slightly ditferent from said predetermined diameterand being in its entirety normally located in said annular space butwith freedom of movement in longitudinal direction of said chamber so asto move in such longitudinal direction during and as the result'ofchanges of the volume of said annular space during movement of saidpiston.

2. A pump as defined in claim 1, wherein said external surface of saidpiston tapers continuously inwardly and defines with said internalsurface said annular space.

3. A pump as defined in claim 1, wherein said annular insert is ofcircular cross-section.

4. A pump as defined in claim 1, wherein said annular insert is of otherthan circular cross-section.

5. A pump as defined in claim 1, wherein said annular insert is ofpolygonal cross-section.

6. A pump as defined in claim 1, wherein said annular insert is oftriangular cross-section.

7. A pump as defined in claim 1, wherein said annular insert is ofelastomeric material.

I 8. A pump as defined in claim 1, wherein said annular insert consistsat least predominantly of cross-linked polyurethene elastomer.

9. A pump as defined in claim 1, wherein said end portions diverge inmutually opposite radial directions, and wherein said annular spacewhich they define together with said diaphragm and with one another isof substantially triangular cross-sectional outline.

References Cited UNITED STATES PATENTS 1,945,181 1/1934 Carter 103-1502,913,007 11/1959 Morrison 103-150 X 3,093,086 6/1963 Altoz et al103-150 1,198,971 9/1916 Taylor 230- 2,782,719 2/ 1957 Geogias 103-1502,853,015 9/1957 Pleuger 103-150 2,846,139 8/1958 Blount et al 230-1702,786,423 3/1957 Coffey 103-150 2,869,474 l/ 1959 Pleuger et al 103-1503,201,136 8/1965 Harrison et al. 260-775 X WILLIAM L. FREEH, PrimaryExaminer US Cl. X.R.

